1. Field of the Invention
The present invention relates generally to Multimedia Broadcast Multicast Services (MBMS) in a wireless cellular network, and more particularly to MBMS for delivery of multimedia content cached in wireless cellular network nodes.
2. Description of Related Art
The evolving mobile market has seen a considerable rise in buyers opting for high end mobile phones, such as smart phones. Wireless communication technologies such as Long Term Evolution (LTE) offering higher data speeds encourage users to use data-intensive multimedia services more frequently. With User Equipment (UE), such as the smart phone, and a Personal Digital Assistant (PDA), subscribed to round-the-clock access to internet services and supported by communication technologies, such as LTE, that offer high speed data rates, mobile video, mobile television, and radio broadcasting are expected to grow rapidly.
Multimedia Broadcast Multicast Services (MBMS) in the LTE network enable network operators to stream multimedia content to the UE. The MBMS architecture enables broadcasting and multicasting of the multimedia content. The broadcast services can be received by any subscriber located in the area in which the service is offered. The multicast services can only be received by users who have subscribed to the specific service and who have joined the multicast group associated with the service. Both broadcast and multicast services are unidirectional, point-to-multipoint transmissions of multimedia content and can be applied to broadcast text, audio, picture, and video from a Broadcast Multicast Service Center (BMSC) to any user located in the service area.
Existing methods providing multimedia content are based on MBMS architecture specified by the 3rd Generation Partnership Project (3GPP). The existing MBMS architecture is based on the assumption that the multimedia content for MBMS is always located in a content provider residing outside of the core network (for example, servers in the Internet Protocol (IP) network). With existing methods, whenever the multimedia content located in the content provider, or any other broadcast/multicast source, is to be delivered (broadcasted or multicasted) to the UEs, the BMSC, which is external to the wireless cellular network, serves as an entry point. The BMSC is a functional entity providing the MBMS service to the end-user.
The BMSC schedules the MBMS session, performs MBMS session announcement and signals the Multi-Cell Multicast Coordination Entity (MCE), through the E-UTRAN internal control (M3) interface, to co-ordinate the MBMS session. The MBMS session is established by setting up a user plane (M1) interface and control plane (M2) interface by the MCE. The MCE is a logical entity, responsible for allocation of time and frequency resources for multi-cell MBMS transmission. The MCE performs the scheduling on the radio interface. The M1 interface is a data path established between a MBMS Gateway (MBMS GW) and the relevant Radio Access Network (RAN) nodes to which the multimedia content is to be forwarded for delivery to the UEs. The M2 interface is established between the MCE and the RAN nodes to exchange control signals for the MBMS session. The M3 interface supports the MBMS session control signaling, such as signaling for session initiation and termination.
Thus, the multimedia content to be delivered to the UEs on the MBMS channels has to pass through the BMSC (i.e., BMSC server). Then, the MBMS GW performs MBMS session management and delivers multimedia content received from the BMSC to the relevant RAN nodes by IP multicast over the established M1 interface.
To optimize delivery of multimedia content to the users, network operators are widely deploying Content Distribution Networks (CDNs). The CDNs can handle backhaul overload issues for the network operators. With wide deployment of CDNs overlaid on top of LTE networks, most of the multimedia content is expected to be cached locally at one or more wireless cellular network nodes, such as RAN nodes, Serving Gateways (SGWs), and/or Packet Data Network gateways (PDNs) within the wireless cellular network. However, the existing methods fail to provide a signaling mechanism that enables the wireless cellular network nodes to notify the MCE about locally available cached content that can be used for MBMS. Also, the existing MBMS procedures rely heavily on core network mechanisms to start and stop MBMS sessions.